1. Field of the Invention
This invention relates generally to optical switching elements, in particular, optical switches implemented using reversible electroplating mirrors.
2. Description of the Related Art
Current state of the art in optical routing and signal switching system is still faced with limitations that the optical switching devices are not able to satisfy many requirements demanded by modern fiber optical communication systems. Specifically, with the advancement of network communication technology, the modern fiber optical communication systems require an optical switch that can be produced at low-cost, has a low power consumption requirement, can achieve fast switching speed, reliable, and scaleable to a large number of ports. However, such optical switch is not yet available. The demand is ever more pressing as much of the information in telecommunication and data communication systems is now carried over optical networks. The amount of information and the speed with which it must be transmitted necessitates the deployment of large number of optical switches that can handle millions of bits per second. The increased amount of information transmitted over optical networks has created a high demand for optical switches, which can switch quickly, and are cost-effective and reliable.
The primary optical switching technologies used today are Micro Electro-Mechanical Systems (MEMS), liquid crystals, and bubbles. Each of these technologies has its advantages and disadvantages. Switching using MEMS-based 2D or 3D tiny mirrors is done using miniaturized mirrors fabricated on a single chip. Although these switches are small in size and can be produced economically, problems arise from their mechanical nature. The moving parts in MEMS-based switches increase switching times, consume more power, and make them difficult to package reliably. Switches that use liquid crystal technologies as described in U.S. Pat. No. 6,266,109 to Yamaguchi et al. and U.S. Pat. No. 6,289,145 to Solgaard et al. rely on polarization changes to reflect light. Since they are solid-state devices, liquid-crystal-based switches do not have the issues MEMS-based switches have regarding switching speeds, power consumption and reliable packaging. The challenge in using liquid crystal technologies for optical switches is that liquid crystal properties change with changes in temperature; thus, the temperature in the switch must be regulated for proper operation. A second problem is that liquid-crystal-based switches do not scale well to a large number of ports. The switches described in U.S. Pat. No. 4,988,157 to Jackel et al. and U.S. Pat. No. 4,988,157 to Fouquet et al., use bubbles created in an index-matching fluid to reflect light. Being solid-state devices, bubble-based switches have similar advantages as liquid-crystal-based switches over mechanical switches. Additionally, bubble-based switches are not affected by the temperature variations that plague liquid-crystal based switches. However, bubble technology has switching reliability problems and insertion loss when used in large-scale switches.
A Reversible Electrochemical Mirror (REM) is one possible technology for building optical switching elements. U.S. Pat. No. 6,111,685 to Tench et al. describes an REM device that is used on building vehicle windows to regulate the amount of sunlight that enters and thus reduce the amount of heat generated (via the greenhouse effect). The disclosure made in U.S. Pat. No. 6,111,685 is hereby incorporated as reference in this Application. In a REM-based smart window, the amount of sunlight that passes through is determined by the reflectivity of the window. Such windows are inexpensive to manufacture, require little voltage to operate, and are highly effective in avoiding inside heating. Although REM technology has been applied to variable-transmission windows, this type of mirror has not been applied to optical switching applications.
Therefore, a need still exists in the art to provide an innovative method for constructing optical switches taking advantage of the REM technologies. It is desirable that the improved optical switch is able to satisfy the requirements that the optical switch can be produced at low-cost, has a low power consumption requirement, can achieve fast switching speed, reliable, and scaleable to a large number of ports is not yet available.